1. Field of the Invention
The present invention relates to a thermoelectric element module and a method for manufacturing the thermoelectric element, and more particularly to a thermocouple-type thermoelectric module configured such that P-type thermoelectric materials and N-type thermoelectric materials are respectively joined between a pair of electrodes, and a method for manufacturing the thermoelectric element.
2. Description of the Related Art
Generally, a thermoelectric element including a thermoelectric converter is configured such that P-type thermoelectric materials and N-type thermoelectric materials are joined between metal electrodes to form a PN junction pair. If different temperatures are endowed to such a PN junction pair, a power is generated due to the Seebeck effect, so the thermoelectric element may function as a power generator. Also, due to the Peltier effect by which one side of the PN junction pair is cooled and the other side is heated, the thermoelectric element may be used as a temperature controller.
FIG. 1 is a partially sectioned perspective view schematically showing a general thermoelectric element module. Referring to FIG. 1, the conventional thermoelectric element module 1 includes P-type thermoelectric materials 3 and N-type thermoelectric materials 5. Electrodes 9 are attached in a predetermined pattern to a pair of insulation substrates 7 made of ceramic or silicon nitride. Such materials 3 and 5 are connected to the electrodes 9 in series.
In the conventional thermoelectric element module 1, if a DC current is applied to the electrode 9 through a lead wire 4 connected to a terminal 2, heat is generated at a side where the current flows from the P-type thermoelectric material 3 to the N-type thermoelectric material 5, and on the contrary heat is absorbed at a side where the current flows from the N-type thermoelectric material 5 to the P-type thermoelectric material 3, by means of the Peltier effect. Thus, the insulation substrate 7 joined to the heat-generating side is heated, and the insulation substrate 7 joined to the heat-absorbing side is cooled. Meanwhile, in the thermoelectric element module 1, if the polarity of the DC current applied to the terminal 2 is reversed, the heat-generating side is replaced with the heat-absorbing side. Also, in the thermoelectric element module 1, if different temperatures are endowed to the pair of insulation substrates 7, voltage is generated at the terminal by means of the Seebeck effect.
In general, the thermoelectric element is used as a module in which several ten or several hundred PN junction pairs are connected in series, as an example. Common thermoelectric element modules are manufactured by mechanically processing a thermoelectric material, which is a single crystal but has an ingot shape made by the directional solidification, into an element of a specific dimension, then joining electrodes to a patterned substrate made of ceramic or silicon nitride, and then joining the electrodes with thermoelectric materials (P-type, N-type). Each of the thermoelectric materials is joined to a corresponding electrode using an adhesive.
However, Bi—Te thermoelectric material of a single crystal or directional solidifier has an inherent plane of cleavage in a crystallographic aspect, so the thermoelectric material may be easily cracked when being processed, which results in a deteriorated recovery rate.
In addition, when manufacturing a thermoelectric element, two joining processes are required. For example, after the electrodes are joined to a metal-plated ceramic substrate, thermoelectric materials should be joined to the electrodes. In this reason, it is complicated to manufacture a thermoelectric element, and also it is difficult to select a joining solder. In more detail, in a conventional thermoelectric element module manufacturing method, several hundred (about 200) thermoelectric material dices of a substantially cuboid shape are manually soldered to an electrode of a substrate, which consumes a lot of labor. Thus, it is substantially impossible to lower a production cost below $10˜$20 per each unit. In addition, if precise dimension control is not ensured, a gap is formed between the thermoelectric material and the electrode, which may cause an inferior junction.
Meanwhile, it may also be considered to mass-product wafer-type thermoelectric elements by means of sputtering, used in a semiconductor manufacture process, in order to lower a price of the module. However, in this case, the element has a very small size, so it is difficult to increase the size of the thermoelectric element module.